Mumbai has perhaps the most extreme statistics of any metropolis. Its land mass is small, stuck like a crooked blade into the Arabian Sea. It has poor transport links, so people who work in the city live near it. That in turn means it has the highest population density of any big city. But it is also low-rise. Panama City has a taller skyline....

Three things explain Mumbai’s predicament: regulations, financing and graft. The city, reckons Edward Glaeser of Harvard University, has “some of the most extreme land-use restrictions in the developing world”, designed to deter new migrants but which have backfired.

The leaders of the 20 major economies (G20) will meet in a summit on June 18–19 at Los Cabos, Mexico. The summit will build on past commitments of the Cannes Declaration inked last year, when the leaders reaffirmed their commitment to rationalizing and phasing out over the medium term inefficient fossil-fuel subsidies that encourage wasteful consumption, while providing targeted support for the poorest people.

The International Monetary Fund (IMF) estimates that fossil-fuel subsidies result in US$500 billion worth of trade lost annually from global gross domestic product (GDP). Focusing on Indonesia as a model for subsidy reform is crucial, as it is one of the four G20 countries that posted positive economic growth beyond 5 percent (6.4 percent) during the financial crisis in 2011.